Stoplog gates are not new in the art. Such gates have long been used to selectively open up or close off a channel to a flow of water. Stoplog gates typically comprise a log-retaining frame having a pair of vertical grooves formed opposite one another in the two opposing side walls of a flow channel, and a variable number of stoplogs which slidably fit into the vertical wall grooves so that each stoplog extends across the channel between the two opposing side walls in a direction perpendicular to the flow of water. With this arrangement the first stoplog introduced into the vertical side grooves slides down along the grooves until it comes to rest on the bottom surface of the channel, and any additional stoplogs subsequently introduced into the vertical side grooves stack one upon another. In this way the stoplogs, in combination with the bottom surface of the channel and the side walls of the channel, form a barrier to the flow of water. By varying the number of stoplogs used in the gate, and also the height of the stoplogs used in the gate, the level of the stoplog barrier within the channel can be regulated as desired.
Early stoplog members were typically formed of logs or simple wooden planks. Later steel and/or concrete beams were also employed as stoplogs. However, since the height of the water barrier in a stoplog gate can only be adjusted by the addition or removal of stoplogs into and out of the vertical grooves formed in the side walls of the channel, it has been found desirable to have the stoplogs formed out of the lightest possible materials in order to facilitate manipulation of the stoplogs. At the same time, however, it has also been found desirable to make the stoplogs as strong as possible so that the stoplogs may adequately resist the force of the water in the channel, and also so that the stoplogs may survive any possible collisions with foreign objects which may be carried along by the water. As a result, efforts have been made to fabricate relatively strong stoplogs out of strong, lightweight materials such as aluminum.
One well-known stoplog design calls for fabricating the stoplogs out of large, thin plates of aluminum attached to and strengthened by an interior aluminum support structure. However, making this type of stoplog tends to be time-consuming and expensive. In addition, the large thin plates of aluminum have exhibited a tendency to become distorted while they are being attached to the interior support structure. Such plate distortion can create problems with introducing or removing stoplogs into or out of the stoplog gate, and may also impede the formation of a watertight barrier by the stoplogs across the channel.
Another known stoplog design addresses these distortion problems by providing an aluminum stoplog which comprises two or more channel-shaped members of extruded aluminum, wherein the two or more members are stacked vertically and parallel on one another and then attached together, e.g., by welding, so as to form a single rigid stoplog of substantially rectangular cross-section, with at least one of the vertical faces of the stoplog being substantially impervious to water. The uppermost member includes at least one mounting hook thereon for coupling the stoplog to stoplog lifting and lowering means, and the lowermost member includes at least one drilled hole for receiving the at least one mounting hook of an adjacent and lower stoplog when a plurality of stoplogs are stacked one above another in a stoplog gate, in order that the presence of the one or more lifting hooks on the top side of the lower stoplog will not impede the formation of a watertight seal between adjacent stoplogs when a plurality of stoplogs are stacked in a stoplog gate. Sealing means, in the form of J-type seals, are also provided about the perimeter of the stoplog to insure a good watertight seal when the stoplog is positioned within the stoplog gate. The seals are mounted to the stoplog by attaching an aluminum strip to a portion of each seal and then bolting the strip to the stoplog using conventional nuts and bolts.
Unfortunately, while such an extruded stoplog design solves the aforementioned distortion problems encountered with other aluminum stoplogs, it has its own set of disadvantages. First, the attachment of the seals to their aluminum mounting strips takes time and effort. Second, the subsequent bolting of the seals to the stoplog involves another time-consuming step in the manufacturing process. Third, the use of J-type seals in the stoplog design means that it is necessary to miter the bulb sections of two perpendicularly-adjoining seals in order to provide a watertight fit between the seals. Fourth, the use of aluminum mounting strips on the seals means that they too must be mitered where seals adjoin one another in order to provide the requisite watertight fit. And fifth, the drilling of holes in the extruded lowermost channel member (to receive the mounting hooks of an adjacent and lower stoplog) means that another time-consuming step is added to the manufacturing process. Furthermore, by using discrete drilled holes to receive the mounting hooks, the stoplog design necessitates that the positions of the mounting hooks and the receiving holes be carefully coordinated with one another to assure proper reception of the mounting hooks within the holes. This means that more time may be required in this stage of the manufacturing process.